Keyboard control mechanism



Madl 15, 1937- c. J. FITCH KEYBOARD CONTROL MECHANISM Filed March 23,1935 FIGA,

Patented Mar. 16, 1937 KEYBOARD CONTROL MECHANISM Clyde J. Fitch. JerseyCity, N. J., assigner to International Business Machin es Corporation,

New York, N. Y., a corporation of New York Application March 23, `1935,Serial No. 12.575

(CL lill-17) 8 Claims.

This invention relates to improvements in keyboard control mechanismsand particularly to mechanisms adapted to control the rate of operationof the keyboard and is especially adaptable to power driven mechanismssuch as typewriters of the type comprising a power driven roller` foractuating the printing instrumentalities.

One of the objects of the present invention is to provide meansgoverning the keyboard opera- 10 tion at various predetermined rates.

Another object of the present invention is the provision for limitingthe rate of speed of depressing the key bars so as to conform with the.selected predetermined rate. j

Still another object of the present invention is to provide for lockingof the keyboard when the device is in an inoperative condition.

Still another object of the present invention is to provide means toprevent the action of the ,o keyboard to increase the selectedpredetermined rate of speed of the keyboard regulating means.

The stated objectives of the invention are accomplished by .providing atransverse bail adapted to be engaged by each key bar upon its depres-25 sion and in addition thereto to be depressed by further depression ofthe key bars. A pawl arrangement is associated with the bail, `so thatupon the depression of the bail, the pawl engages a continuouslyrotating ratchet wheel. The 30 ratchet wheel may be rotated at variousspeeds in accordance with the desired rate of operation of the keyboard.4

Therefore, upon depressing the different keys at a rate exceeding thefixed speed of the ratchet 35 wheel. the pawl engages the face of theteeth, re-

tarding the complete depression of the keys until the teeth of theratchet wheel have been advanced to permit the pawl to travel its fullstroke.

In this manner the device tends to regulate the 40 operation of thekeyboard to conform to the rate of speed for which it is adjusted. Inaddition thereto, it also tends to promote rhythmic operation of thekeyboard in contra-distinction to irregular and spasmodic operationthereof.

4 A worm drive is provided for the said ratchet wheel so that when themechanism is set for a predetermined rate of speed, it is impossible toforce the ratchet wheel to rotate faster than its predetermined speed byexerting extremely hard pressure on the keys. f

A further feature of the invention is that th transverse bail acts as akeyboard lock when the drive mechanism and ratchet wheel are at rest, 55in'V this manner preventing the depression of the individual key barswhen the mechanism is in an inoperative condition.

Various other objects and advantages of the invention will be obviousfrom the following particular description of one form of mechanismembodying the invention or from an inspection of the accompanyingdrawing; and the invention also constitutes certain new and usefulfeatures of construction and combination of parts hereinafter set forthand claimed.

In the drawing:

Fig. 1 shows a sectional elevation of one form of mechanism embodyingthe present invention.

Fig. 2 shows a plan view oi the control mechanism.

Fig. 3 shows a detail of the pawl and ratchet arrangement, and is asectional view along line 3--3 of Fig. i.

This invention can be embodied in a considerable variety ofconstructions, and of these one has been selected for speciiicdescription and illustration herein, the one which at the present timeis believed to exhibit the invention in its most convenient andeffective form. 'Ihe construction referred to is one form of awell-known recording unit and described in a copending application,Serial No. 677,018, iiled June 22, 1933.

Referring now to the drawing in which similar parts are designated bythe same numerals in the several views, it is believed that a clearunderstanding of the invention will be had therefrom when considered inconjunction with the following description.

As mentioned before for illustrative purposes, this invention is shownembodied in a power driventypewriter of the type disclosed in theaforesaid application, the construction of which is well known to thosein the art, and hence requires only the following brief description.

Transmttttny unit Referring to the drawing, and in prticular to Fig.' 1,in the embodiment illustrated in the drawing, well known means areprovided for actuating the type bars (not shown) by power operateddevices comprising a power driven roller i0.

A cam Il is pivoted on one arm of a bell crank lever I2 pivoted in theframe, the other arm of which is operatively connected with one armof abell crank lever i! by means of link il. The other arm of lever Il isconnected to the type bars (not shown) in a well known manner and fullydisclosed in the aforesaid application.

The lever I2 is actuated by the cam Il when. the latter engages thedriven roller I0 to be operated thereby. The engagement of the cam Ilwith the power roller is controlled by means of the key lever I1 in amanner which will now be described.

The cam II is resiliently engaged by a springpressed arm 20 which tendsto turn it into engagement with the power driven roller or stop 2I on alever 22 pivoted on the bell crank I2 and normally arranged in the pathof a lug on the cam. When the lever 22 swings to move its stop out ofthe path of the lug, the arm 20 swings the cam into engagement with thepower roller to be actuated thereby to swing the bell crank I2 toactuate its connected mechanism.

I'he lever 22 has an arm 24 which is provided with an offset projection25 at its end whichv projects laterally through an opening in the bellcrank I2 and engages the bifurcated lower end 26 of an arm 21 of a keylever I1 pivoted on the common rod 28.

It is obvious then that depression of a key lever I1 releases therevolubly mounted cam II to engage and be actuated by power roller I0 inturn operating bell crank I2 and its attached links to cause theassociated mechanism, such as the key bars and other operatingmechanisms, to be operated.

It will be understood that the usual number of key bars and powerdevices with their associated mechanisms are provided, but only one ofthem is shown for the sake of clearness.

A driving pulley 35 attached to power driven roller I0 rotates the shaft36 and attached worm gear 31 at a constant speed by means of the drivenpulley 39 fixed on shaft 36 and a suitable connecting belt 39. Asuitable member 46 fastened to the frame 4Ia of the typewriter, inaddition to supporting the shaft 36 supports shaft 4| with its attachedratchet wheel 42 and worm gear 43. An extension arm 44 of the frame 40supports one end of shaft 46, the other end of which is suitablysupported by a member 46 fastened to the frame of the typewriter. Fixedto the said member 46 is a spring blade 4'lV adapted to engage a pin 48protruding from a bail member 49. The bail member fixed to shaft 45 isdisposed beneath the key bars I'I of the typewriter in such a mannerthat any depressed key bar I1 engages the bail 49 to depress the saidbail against the action of spring blade 41, which restores the bail toits normal position upon release of the key. bar.. A pawl supportingmember 50, suitably fixed to the bail 49 and extending therefrom,retains a spring-pressed pawl 5I pivoted on stud 52. It is evident fromthis descriptio that upon depressionv of the bail member 49 caused bythe depression of a key bar I'I, the pawl 5I is adapted to engage theteeth of ratchet wheel 42. The speed of rotation of the said ratchetwheel is controlled by the driven power roller I0 the speed of which maybe adjusted to any desired rate.

Therefore, it is seen, that the ratchet wheel 42 is rotated at apredetermined rate of speed and let it be assumed that this rate permitsthe different key bars I1 to be depressed at an even rate equivalent to60 five-character words per minute; i. e., the teeth of ratchet wheel 42are advanced beyond the established point or axis of contact by pawl 5I,so as to permit the bail 49 and member 50 to be lowered or depressed 300times per minute so that the retained springpressed pawl 5I travels itsfull stroke upon the depression of each key bar. In the event that thekey bars are depressed at a faster .rate or at an uneven rate, thedepressed pawl tends to engage the faces of the teeth of the ratchetwheel and in this manner opposes further depression of the key bars atthat exact moment. As the teeth of the ratchet wheel are advanced thepawl can freely be depressed the full depth of its stroke in turnpermitting the key bars to be fully de pressed with ease. y

In this manner the keyboard 'action can be controlled to regulate thespeed of operation thereof. When operated at the predetermined rate, orless than the predetermined rate, corresponding to the selected speed ofthe ratchet wheel and at an even and rhythmic rate, the keyboard is freeacting and any opposition to the depression of the key bars is notpresent, however, any operation of the key bars faster than thepredetermined rate selected will cause the action of the keyboard not tobe free acting in the sense that the action of the key bars will bequite firm in resisting the depression thereof.

It was mentioned hereinbefore that this device is not limited in itsapplication to power driven key operated mechanisms, and it is obviousthat it may be applied to any form of key operated device. In the eventthat the device is ap plied to non-power operated mechanisms the shaft36 can be rotated by an individual motor or suitable power source.

It was also mentioned hereinbefore that a 4worm drive 31, 43 is providedto rotate the ratchet wheel 42. 'I'he provision of this type of driveprevents the ratchet wheel from being driven by the pawl mechanism 5I ata speed faster than the predetermined rate of speed selected for theratchet wheel, by means of exerting extremely hard pressure on theindividual key bars.

Furthermore, the device just described acts as a keyboard lock, that is,preventing the depression of the individual key bars, when the ratchetwheel 42 is in an inoperative or non-rotating condition. With themechanism at rest, the pawl mechanism 5|cannot travel the full length ofits stroke, since it is necessary for the ratchet teeth to be advancedto permit this action, and therefore the bail member 49 is preventedfrom being depressed, in turn rendering the keyboard inoperative or in alocked condition when the ratchet wheel is at rest.

While there has been shown and described and pointed out the fundamentalnovel features of the invention as applied to a single modification. itwill be understood that various omissions and substitutions and changesin the form and details of the device illustrated and in its operationmay be made by those skilled in the art without departing from thespirit of the invention. It is the intention therefore to be limitedonly as indicated by the scope of the following claims.

What is claimed is as follows:

1. A keyboard controlling mechanism comprising a. cyclically operatedmember adapid to be operated at a selected predetermined rate of speed,a plurality of operable key bars, and a common means associated with thesaid key bars and controlled by the said member to regulate the rate ofoperation of the said key bars in accordance with the selected rate ofoperation of the said member.

2. A keyboard controlling mechanism comprising a constantly rotatingdevice adapted to be rotated at selective rates of speed, a plurality ofoperable key bars, anda common means jointly controlled by the keybarsand the rotary device to regulate the rate of operation of the said keybars in accordance with the selected rate of operation 'of the saiddevice.

3. A keyboard controlling mechanism comprising a rotating ratchet wheeladapted to be operated at a selected predetermined speed, a plurality ofoperable key bars, and a common pawl mechanism operated by the operationof any one of the said key bars so as to engage the said ratchet wheelto regulate the rate of operation of the said key bars in accordancewith the selected speed oi the ratchet wheel.

4. A keyboard controlling mechanism comprising a rotary member adaptedto be operated at a selected predetermined speed, a plurality ofoperable key bars, a common means associated with the said key barsadapted to be operated upon the ,depression of any one of the key bars,and a mechanism adapted to cooperate with the said rotary membercontrolled by the said means upon operation of the selected key bars, toregulate the rate of operation of the selected key bars in accordancewith the selected speed of the rotary member. s

5. In a typewriting machine, the combination of printinginstrumentalities, power driven meansv for actuating saidinstrumentalities, keys for controlling the operation of said printinginstrumentalities, a cyclicaliy operated member responsive to said powerdriven means and adapted' to be operated at a selected predeterminedrateof speed, means associated with the said keys and controlled by saidmember to regulate the rate of operation of the said keys in accordancewith the'selected rate of operation of the said member.

6. A keyboard controlling mechanism comprising a member adapted to beoperated at a. predetermined speed, means to operate said member. aplurality of operable key bars, common means controlled by the operationof any one of the said key bars and controlled by the said member toregulate the rate of operation of the said key bars in accordance withthe speed of operation of the said member, said common means associatedwith the said member so as to prevent the operation of any one of thesaid key bars when the said member is not operated.

7. A keyboard controlling mechanism comprising a cyclically operatedmember adapted to be operated at a predetermined rate oi' speed, aplurality of operable key bars, a transverse bail associated with thesaid key bars and arranged to be operated upon the operation of a keybar, and mueans controlled by the said bail and member to regulate therate of operation of the said key bars in accordance with the rate ofoperation of the saidmember. l

8. A keyboard controlling mechanism comprising a cyclically operatedmember adapted to be operated at a predetermined rate of speed, aplurality of operable key bars, a transverse bail associated with thesaid key bars and arranged to be responsive to the operation of the saidkey bars. and a pawl mechanism controlled by said bail and member toregulate-the rate of operation of thei said key bars in accordance withthe rate ot operation of the said member.

l CLYDE J. ITI'CH.

